Immunogenic conjugates have been made by forming a Schiff base between a linear alkylaldehyde and a linear alkylamine. However, the linkages in such conjugates are reversible at physiological pH (pH of about 6 to about 8) unless treated with sodiumborohydride to convert the compounds to diakylamines. In addition, antigen-carrier conjugation via alkyl-aldehyde and amine by reductive amination is commonly used. King et al., Preparation of Protein Conjugates via Intermolecular Hydrazone Linkage, Biochemistry 1986, 25, 5774-5779 describes a method for conjugating proteins that involves forming a hydrazone linkage between two proteins, but the hydrazone linkage is reversible and must be subject to reduction to form a more stable hydrazide bond. However, the reduction reaction used in all of these conjugation methods to improve stability typically involves a long exposure to boron-hydride. However, in the case of disulfide-containing carrier proteins and antigens, prolonged exposure to boron-hydride is a potential problem since it can also reduce the disulfide bonds in the carrier protein and alter its structure. Thus, it would be advantageous to have immunogenic conjugates that are not reversible at physiological pH, and that do not require reduction with boron-hydride.